summaryrefslogtreecommitdiff
path: root/headers.c
blob: fae683a631556878fbe189d975d57211b8e9f318 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
/* 
 * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
 * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
 * Copyright (c) 1996 by Silicon Graphics.  All rights reserved.
 *
 * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
 * OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.
 *
 * Permission is hereby granted to use or copy this program
 * for any purpose,  provided the above notices are retained on all copies.
 * Permission to modify the code and to distribute modified code is granted,
 * provided the above notices are retained, and a notice that the code was
 * modified is included with the above copyright notice.
 */
 
/*
 * This implements:
 * 1. allocation of heap block headers
 * 2. A map from addresses to heap block addresses to heap block headers
 *
 * Access speed is crucial.  We implement an index structure based on a 2
 * level tree.
 */
 
# include "gc_priv.h"

bottom_index * GC_all_bottom_indices = 0;
 
/* Non-macro version of header location routine */
hdr * GC_find_header(h)
ptr_t h;
{
#   ifdef HASH_TL
	register hdr * result;
	GET_HDR(h, result);
	return(result);
#   else
	return(HDR_INNER(h));
#   endif
}
 
/* Routines to dynamically allocate collector data structures that will */
/* never be freed.							 */
 
static ptr_t scratch_free_ptr = 0;
 
ptr_t GC_scratch_end_ptr = 0;

ptr_t GC_scratch_last_end_ptr = 0;
		/* End point of last obtained scratch area */
 
ptr_t GC_scratch_alloc(bytes)
register word bytes;
{
    register ptr_t result = scratch_free_ptr;

#   ifdef ALIGN_DOUBLE
#	define GRANULARITY (2 * sizeof(word))
#   else
#	define GRANULARITY sizeof(word)
#   endif
    bytes += GRANULARITY-1;
    bytes &= ~(GRANULARITY-1);
    scratch_free_ptr += bytes;
    if (scratch_free_ptr <= GC_scratch_end_ptr) {
        return(result);
    }
    {
        word bytes_to_get = MINHINCR * HBLKSIZE;
         
        if (bytes_to_get <= bytes) {
          /* Undo the damage, and get memory directly */
	    bytes_to_get = bytes;
#	    ifdef USE_MMAP
		bytes_to_get += GC_page_size - 1;
		bytes_to_get &= ~(GC_page_size - 1);
#	    endif
   	    result = (ptr_t)GET_MEM(bytes_to_get);
            scratch_free_ptr -= bytes;
	    GC_scratch_last_end_ptr = result + bytes;
            return(result);
        }
        result = (ptr_t)GET_MEM(bytes_to_get);
        if (result == 0) {
#	    ifdef PRINTSTATS
                GC_printf0("Out of memory - trying to allocate less\n");
#	    endif
            scratch_free_ptr -= bytes;
	    bytes_to_get = bytes;
#	    ifdef USE_MMAP
		bytes_to_get += GC_page_size - 1;
		bytes_to_get &= ~(GC_page_size - 1);
#	    endif
            return((ptr_t)GET_MEM(bytes_to_get));
        }
        scratch_free_ptr = result;
        GC_scratch_end_ptr = scratch_free_ptr + bytes_to_get;
        GC_scratch_last_end_ptr = GC_scratch_end_ptr;
        return(GC_scratch_alloc(bytes));
    }
}

static hdr * hdr_free_list = 0;

/* Return an uninitialized header */
static hdr * alloc_hdr()
{
    register hdr * result;
    
    if (hdr_free_list == 0) {
        result = (hdr *) GC_scratch_alloc((word)(sizeof(hdr)));
    } else {
        result = hdr_free_list;
        hdr_free_list = (hdr *) (result -> hb_next);
    }
    return(result);
}

static void free_hdr(hhdr)
hdr * hhdr;
{
    hhdr -> hb_next = (struct hblk *) hdr_free_list;
    hdr_free_list = hhdr;
}
 
void GC_init_headers()
{
    register unsigned i;
    
    GC_all_nils = (bottom_index *)GC_scratch_alloc((word)sizeof(bottom_index));
    BZERO(GC_all_nils, sizeof(bottom_index));
    for (i = 0; i < TOP_SZ; i++) {
        GC_top_index[i] = GC_all_nils;
    }
}

/* Make sure that there is a bottom level index block for address addr  */
/* Return FALSE on failure.						*/
static GC_bool get_index(addr)
register word addr;
{
    register word hi =
    		(word)(addr) >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE);
    register bottom_index * r;
    register bottom_index * p;
    register bottom_index ** prev;
#   ifdef HASH_TL
      register unsigned i = TL_HASH(hi);
      register bottom_index * old;
      
      old = p = GC_top_index[i];
      while(p != GC_all_nils) {
          if (p -> key == hi) return(TRUE);
          p = p -> hash_link;
      }
      r = (bottom_index*)GC_scratch_alloc((word)(sizeof (bottom_index)));
      if (r == 0) return(FALSE);
      BZERO(r, sizeof (bottom_index));
      r -> hash_link = old;
      GC_top_index[i] = r;
#   else
      if (GC_top_index[hi] != GC_all_nils) return(TRUE);
      r = (bottom_index*)GC_scratch_alloc((word)(sizeof (bottom_index)));
      if (r == 0) return(FALSE);
      GC_top_index[hi] = r;
      BZERO(r, sizeof (bottom_index));
# endif
    r -> key = hi;
    /* Add it to the list of bottom indices */
      prev = &GC_all_bottom_indices;
      while ((p = *prev) != 0 && p -> key < hi) prev = &(p -> asc_link);
      r -> asc_link = p;
      *prev = r;
    return(TRUE);
}

/* Install a header for block h.  */
/* The header is uninitialized.	  */
/* Returns FALSE on failure.	  */
GC_bool GC_install_header(h)
register struct hblk * h;
{
    hdr * result;
    
    if (!get_index((word) h)) return(FALSE);
    result = alloc_hdr();
    SET_HDR(h, result);
    return(result != 0);
}

/* Set up forwarding counts for block h of size sz */
GC_bool GC_install_counts(h, sz)
register struct hblk * h;
register word sz; /* bytes */
{
    register struct hblk * hbp;
    register int i;
    
    for (hbp = h; (char *)hbp < (char *)h + sz; hbp += BOTTOM_SZ) {
        if (!get_index((word) hbp)) return(FALSE);
    }
    if (!get_index((word)h + sz - 1)) return(FALSE);
    for (hbp = h + 1; (char *)hbp < (char *)h + sz; hbp += 1) {
        i = HBLK_PTR_DIFF(hbp, h);
        SET_HDR(hbp, (hdr *)(i > MAX_JUMP? MAX_JUMP : i));
    }
    return(TRUE);
}

/* Remove the header for block h */
void GC_remove_header(h)
register struct hblk * h;
{
    hdr ** ha;
    
    GET_HDR_ADDR(h, ha);
    free_hdr(*ha);
    *ha = 0;
}

/* Remove forwarding counts for h */
void GC_remove_counts(h, sz)
register struct hblk * h;
register word sz; /* bytes */
{
    register struct hblk * hbp;
    
    for (hbp = h+1; (char *)hbp < (char *)h + sz; hbp += 1) {
        SET_HDR(hbp, 0);
    }
}

/* Apply fn to all allocated blocks */
/*VARARGS1*/
void GC_apply_to_all_blocks(fn, client_data)
void (*fn)(/* struct hblk *h, word client_data */);
word client_data;
{
    register int j;
    register bottom_index * index_p;
    
    for (index_p = GC_all_bottom_indices; index_p != 0;
         index_p = index_p -> asc_link) {
        for (j = BOTTOM_SZ-1; j >= 0;) {
            if (!IS_FORWARDING_ADDR_OR_NIL(index_p->index[j])) {
                if (index_p->index[j]->hb_map != GC_invalid_map) {
                    (*fn)(((struct hblk *)
                  	      (((index_p->key << LOG_BOTTOM_SZ) + (word)j)
                  	       << LOG_HBLKSIZE)),
                          client_data);
                }
                j--;
             } else if (index_p->index[j] == 0) {
                j--;
             } else {
                j -= (word)(index_p->index[j]);
             }
         }
     }
}

/* Get the next valid block whose address is at least h	*/
/* Return 0 if there is none.				*/
struct hblk * GC_next_block(h)
struct hblk * h;
{
    register bottom_index * bi;
    register word j = ((word)h >> LOG_HBLKSIZE) & (BOTTOM_SZ-1);
    
    GET_BI(h, bi);
    if (bi == GC_all_nils) {
        register word hi = (word)h >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE);
        bi = GC_all_bottom_indices;
        while (bi != 0 && bi -> key < hi) bi = bi -> asc_link;
        j = 0;
    }
    while(bi != 0) {
        while (j < BOTTOM_SZ) {
            if (IS_FORWARDING_ADDR_OR_NIL(bi -> index[j])) {
                j++;
            } else {
                if (bi->index[j]->hb_map != GC_invalid_map) {
                    return((struct hblk *)
                  	      (((bi -> key << LOG_BOTTOM_SZ) + j)
                  	       << LOG_HBLKSIZE));
                } else {
                    j += divHBLKSZ(bi->index[j] -> hb_sz);
                }
            }
        }
        j = 0;
        bi = bi -> asc_link;
    }
    return(0);
}